METAL-ION COMPLEXATION BY THE PHOSPHORYL AND THE CARBONYL GROUPS PROBED BY O-17 NMR-SPECTROSCOPY

Interactions between compounds containing phosphoryl, carbonyl, or hyd roxyl groups (or combinations of these groups) with metal ions (Na+, M g2+)were probed in CD3CN solutions by O-17 NMR spectroscopy, For all p hosphoryl and carbonyl substrates a strong high-field shift of the P=O and C=O signals was observed on the addition of a salt; no shift was observed, however, for the OH group signal, indicating that no chelati on takes place in the hydroxyphosphoryl (or hydroxycarbonyl) derivativ es. For 2-hydroxy-3-benzoylpropylphosphonic diester the O-17 NMR studi es, together with conformational analysis based on the H-1 spectroscop y, demonstrated the chelation of a metal ion by the P=O and C=O functi ons (formation of an eight-membered cyclic structure) with the OH grou p involved in the intramolecular hydrogen bonding, but not in the comp lexation to the metal ion.